The present invention relates to a novel binder composition for pelletized and compressed animal feed. This binder comprises a molasses-free chemically reactive mixture of a reactive phosphate source plus a reactive metal oxide, hydroxide, or salt. This binder is effective in pelletizing dry animal feed ingredients containing less than about 5 percent by weight molasses.
In recent years, pelleted animal feed has become a dominant factor in feeding of both monogastric and ruminent animals Pelleted feeds are also useful in the aquaculture industry, including the feeding of finned fish and crustaceans. There are several advantages to feeding pelleted feeds: (1) pelleted feed prevents selective feeding on those ingredients in the formulation which are more palatable and thus more desirable to the animal; (2) pelleting of the feed ration prevents segregation of the varying size and density constituents which are inherent in animal feeds; (3) pelleting animal feed results in higher bulk density, which is advantageous for both shipping and handling, resulting in maximum load efficiency and reduced storage requirements; (4) pelleting also increases nutritional utilization of the feed components, thus increasing conversion rate of the feed formulation.
Feed pelleting is, as commonly practiced, an extrusion type thermoplastic molding operation in which finely divided particles of a feed ration are formed into compact, easily handled pellets To improve the strength and durability, and to reduce fines produced during the pelleting process, several feed binder additives have been recommended. One of the commonly used ingredients for such purpose is molasses However, this product tends to undesirably reduce lubrication of the feed ingredients through the die of the pelleting equipment, resulting in decreased production rates and increased energy costs. Accordingly, the presence of molasses may be considered undesirable in feed compositions to be subjected to pelleting.
An example of a feed supplement in block form is set forth in U.S. Pat. No. 4,027,043, of Schroeder et al. This patent teaches an animal feed supplement which contains a major proportion of molasses (45 to 93 weight percent) and solidifying components consisting of a phosphate or phosphoric acid and a metal salt or oxide in sufficient quantities and proportions to solidify the product. The compositions are prepared by dispersing the solid ingredients into the liquids, and heating to a temperature of about 95.degree. F. The mixture thickens after about 30 minutes, and is pumped into suitable packaging containers for solidification, shipping, and storage. It is to be noted that Schroeder et al do not teach pelletizing or compression of their feed compositions, and that such compositions are very high in molasses content. While the patent theorizes that a metathesis reaction occurs between soluble phosphates and metal additives, it is equally possible that the mechanism of the Schroeder et al "solidification" is merely a variant of the Steffen Process, as set forth in Beet-Sugar Technology, 3rd Edition, R.A. McGinnis ed., pp. 595-616, Beet Sugar Development Foundation, 1982. In the Steffen Process, sucrose is recovered from beet molasses by reacting with calcium oxide to form an insoluble product, filtering out the sucrose-containing precipitate, decomposing the precipitate by carbonation, and filtering off the alkaline-earth carbonate to leave relatively pure sucrose in solution. The precipitation step of this process is widely believed to be a surface (adsorption) phenomenon (see pp. 605-607). The method of Schroeder et al involves heating the mixture of feed ingredients and solidifications additives to about 90-100.degree. F., with solidification starting after about 30 minutes and continuing during cooling for at least 8 to 10 hours. Such time frames are more consistent with a surface phenomenon precipitation such as in the Steffen Process than with a metathesis (double decomposition) reaction as theorized. In any event, the Schroeder et al reference teaches a solidification of a high molasses content liquid phase material, requiring the elimination or binding of water. The high molasses content of Schroeder et al would preclude pelletizing.
Another reference teaching the preparation of an animal feed block is U.S. Pat. No. 3,532,503, of Kviesitis. This reference indicates that dry feed components may be mixed with liquid molasses, dried, mixed with minor ingredients, treated with surface active emulsion, and treated with steam to activate the adhesive properties of the molasses, and formed into blocks by compression. Kviesitis clearly relies upon molasses as the binder of his feed composition, and desires a high concentration thereof, as evidenced by his adding further molasses as a liquid binder. As in Schroeder et al, the binding mechanism of Kviesitis requires the involvement of molasses.
Additional materials which have been recommended and used as binders, or binding agents, for pelleting animal feeds include clays, in particular bentonite clay and attapulgite clay; lignin sulfonates, a by-product of the paper pulping industry; and gums, such as natural cellulose gum combinations. In addition, such products as sodium carboxymethylcellulose have been used to increase pellet quality.
The clays and lignin sulfonate products are normally employed as binding agents at rates of from 1.5 percent to 3.5 percent by weight. Nutrient value of such products, however, particularly the clays, is minimal, so considerable volume is used in the formulation with little or no contribution to nutritional value. Gums are normally used at much lower concentrations; in the range of 0.05 percent to 0.2 percent, by weight. However, the cost of such materials often precludes their use, particularly at higher, more effective concentrations.